/*
 *  linux/fs/affs/namei.c
 *
 *  (c) 1996  Hans-Joachim Widmaier - Rewritten
 *
 *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
 *
 *  (C) 1991  Linus Torvalds - minix filesystem
 */

#include "affs.h"

typedef int (*toupper_t)(int);

static int       affs_toupper(int ch);
static int       affs_hash_dentry(const struct dentry *, struct qstr *);
static int       affs_compare_dentry(const struct dentry *parent, const struct dentry *dentry,
                unsigned int len, const char *str, const struct qstr *name);
static int       affs_intl_toupper(int ch);
static int       affs_intl_hash_dentry(const struct dentry *, struct qstr *);
static int       affs_intl_compare_dentry(const struct dentry *parent, const struct dentry *dentry,
                unsigned int len, const char *str, const struct qstr *name);

const struct dentry_operations affs_dentry_operations = {
        .d_hash         = affs_hash_dentry,
        .d_compare      = affs_compare_dentry,
};

const struct dentry_operations affs_intl_dentry_operations = {
        .d_hash         = affs_intl_hash_dentry,
        .d_compare      = affs_intl_compare_dentry,
};


/* Simple toupper() for DOS\1 */

static int
affs_toupper(int ch)
{
        return ch >= 'a' && ch <= 'z' ? ch -= ('a' - 'A') : ch;
}

/* International toupper() for DOS\3 ("international") */

static int
affs_intl_toupper(int ch)
{
        return (ch >= 'a' && ch <= 'z') || (ch >= 0xE0
                && ch <= 0xFE && ch != 0xF7) ?
                ch - ('a' - 'A') : ch;
}

static inline toupper_t
affs_get_toupper(struct super_block *sb)
{
        return AFFS_SB(sb)->s_flags & SF_INTL ? affs_intl_toupper : affs_toupper;
}

/*
 * Note: the dentry argument is the parent dentry.
 */
static inline int
__affs_hash_dentry(struct qstr *qstr, toupper_t toupper, bool notruncate)
{
        const u8 *name = qstr->name;
        unsigned long hash;
        int i;

        i = affs_check_name(qstr->name, qstr->len, notruncate);
        if (i)
                return i;

        hash = init_name_hash();
        i = min(qstr->len, 30u);
        for (; i > 0; name++, i--)
                hash = partial_name_hash(toupper(*name), hash);
        qstr->hash = end_name_hash(hash);

        return 0;
}

static int
affs_hash_dentry(const struct dentry *dentry, struct qstr *qstr)
{
        return __affs_hash_dentry(qstr, affs_toupper,
                                  affs_nofilenametruncate(dentry));

}

static int
affs_intl_hash_dentry(const struct dentry *dentry, struct qstr *qstr)
{
        return __affs_hash_dentry(qstr, affs_intl_toupper,
                                  affs_nofilenametruncate(dentry));

}

static inline int __affs_compare_dentry(unsigned int len,
                const char *str, const struct qstr *name, toupper_t toupper,
                bool notruncate)
{
        const u8 *aname = str;
        const u8 *bname = name->name;

        /*
         * 'str' is the name of an already existing dentry, so the name
         * must be valid. 'name' must be validated first.
         */

        if (affs_check_name(name->name, name->len, notruncate))
                return 1;

        /*
         * If the names are longer than the allowed 30 chars,
         * the excess is ignored, so their length may differ.
         */
        if (len >= 30) {
                if (name->len < 30)
                        return 1;
                len = 30;
        } else if (len != name->len)
                return 1;

        for (; len > 0; len--)
                if (toupper(*aname++) != toupper(*bname++))
                        return 1;

        return 0;
}

static int
affs_compare_dentry(const struct dentry *parent, const struct dentry *dentry,
                unsigned int len, const char *str, const struct qstr *name)
{

        return __affs_compare_dentry(len, str, name, affs_toupper,
                                     affs_nofilenametruncate(parent));
}

static int
affs_intl_compare_dentry(const struct dentry *parent, const struct dentry *dentry,
                unsigned int len, const char *str, const struct qstr *name)
{
        return __affs_compare_dentry(len, str, name, affs_intl_toupper,
                                     affs_nofilenametruncate(parent));

}

/*
 * NOTE! unlike strncmp, affs_match returns 1 for success, 0 for failure.
 */

static inline int
affs_match(struct dentry *dentry, const u8 *name2, toupper_t toupper)
{
        const u8 *name = dentry->d_name.name;
        int len = dentry->d_name.len;

        if (len >= 30) {
                if (*name2 < 30)
                        return 0;
                len = 30;
        } else if (len != *name2)
                return 0;

        for (name2++; len > 0; len--)
                if (toupper(*name++) != toupper(*name2++))
                        return 0;
        return 1;
}

int
affs_hash_name(struct super_block *sb, const u8 *name, unsigned int len)
{
        toupper_t toupper = affs_get_toupper(sb);
        int hash;

        hash = len = min(len, 30u);
        for (; len > 0; len--)
                hash = (hash * 13 + toupper(*name++)) & 0x7ff;

        return hash % AFFS_SB(sb)->s_hashsize;
}

static struct buffer_head *
affs_find_entry(struct inode *dir, struct dentry *dentry)
{
        struct super_block *sb = dir->i_sb;
        struct buffer_head *bh;
        toupper_t toupper = affs_get_toupper(sb);
        u32 key;

        pr_debug("%s(\"%.*s\")\n",
                 __func__, (int)dentry->d_name.len, dentry->d_name.name);

        bh = affs_bread(sb, dir->i_ino);
        if (!bh)
                return ERR_PTR(-EIO);

        key = be32_to_cpu(AFFS_HEAD(bh)->table[affs_hash_name(sb, dentry->d_name.name, dentry->d_name.len)]);

        for (;;) {
                affs_brelse(bh);
                if (key == 0)
                        return NULL;
                bh = affs_bread(sb, key);
                if (!bh)
                        return ERR_PTR(-EIO);
                if (affs_match(dentry, AFFS_TAIL(sb, bh)->name, toupper))
                        return bh;
                key = be32_to_cpu(AFFS_TAIL(sb, bh)->hash_chain);
        }
}

struct dentry *
affs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
        struct super_block *sb = dir->i_sb;
        struct buffer_head *bh;
        struct inode *inode = NULL;

        pr_debug("%s(\"%.*s\")\n",
                 __func__, (int)dentry->d_name.len, dentry->d_name.name);

        affs_lock_dir(dir);
        bh = affs_find_entry(dir, dentry);
        affs_unlock_dir(dir);
        if (IS_ERR(bh))
                return ERR_CAST(bh);
        if (bh) {
                u32 ino = bh->b_blocknr;

                /* store the real header ino in d_fsdata for faster lookups */
                dentry->d_fsdata = (void *)(long)ino;
                switch (be32_to_cpu(AFFS_TAIL(sb, bh)->stype)) {
                //link to dirs disabled
                //case ST_LINKDIR:
                case ST_LINKFILE:
                        ino = be32_to_cpu(AFFS_TAIL(sb, bh)->original);
                }
                affs_brelse(bh);
                inode = affs_iget(sb, ino);
                if (IS_ERR(inode))
                        return ERR_CAST(inode);
        }
        d_add(dentry, inode);
        return NULL;
}

int
affs_unlink(struct inode *dir, struct dentry *dentry)
{
        pr_debug("%s(dir=%d, %lu \"%.*s\")\n",
                 __func__, (u32)dir->i_ino, dentry->d_inode->i_ino,
                (int)dentry->d_name.len, dentry->d_name.name);

        return affs_remove_header(dentry);
}

int
affs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
{
        struct super_block *sb = dir->i_sb;
        struct inode    *inode;
        int              error;

        pr_debug("%s(%lu,\"%.*s\",0%ho)\n",
                 __func__, dir->i_ino, (int)dentry->d_name.len,
                 dentry->d_name.name,mode);

        inode = affs_new_inode(dir);
        if (!inode)
                return -ENOSPC;

        inode->i_mode = mode;
        mode_to_prot(inode);
        mark_inode_dirty(inode);

        inode->i_op = &affs_file_inode_operations;
        inode->i_fop = &affs_file_operations;
        inode->i_mapping->a_ops = (AFFS_SB(sb)->s_flags & SF_OFS) ? &affs_aops_ofs : &affs_aops;
        error = affs_add_entry(dir, inode, dentry, ST_FILE);
        if (error) {
                clear_nlink(inode);
                iput(inode);
                return error;
        }
        return 0;
}

int
affs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
        struct inode            *inode;
        int                      error;

        pr_debug("%s(%lu,\"%.*s\",0%ho)\n",
                 __func__, dir->i_ino, (int)dentry->d_name.len,
                 dentry->d_name.name, mode);

        inode = affs_new_inode(dir);
        if (!inode)
                return -ENOSPC;

        inode->i_mode = S_IFDIR | mode;
        mode_to_prot(inode);

        inode->i_op = &affs_dir_inode_operations;
        inode->i_fop = &affs_dir_operations;

        error = affs_add_entry(dir, inode, dentry, ST_USERDIR);
        if (error) {
                clear_nlink(inode);
                mark_inode_dirty(inode);
                iput(inode);
                return error;
        }
        return 0;
}

int
affs_rmdir(struct inode *dir, struct dentry *dentry)
{
        pr_debug("%s(dir=%u, %lu \"%.*s\")\n",
                __func__, (u32)dir->i_ino, dentry->d_inode->i_ino,
                 (int)dentry->d_name.len, dentry->d_name.name);

        return affs_remove_header(dentry);
}

int
affs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
        struct super_block      *sb = dir->i_sb;
        struct buffer_head      *bh;
        struct inode            *inode;
        char                    *p;
        int                      i, maxlen, error;
        char                     c, lc;

        pr_debug("%s(%lu,\"%.*s\" -> \"%s\")\n",
                 __func__, dir->i_ino, (int)dentry->d_name.len,
                 dentry->d_name.name, symname);

        maxlen = AFFS_SB(sb)->s_hashsize * sizeof(u32) - 1;
        inode  = affs_new_inode(dir);
        if (!inode)
                return -ENOSPC;

        inode->i_op = &affs_symlink_inode_operations;
        inode->i_data.a_ops = &affs_symlink_aops;
        inode->i_mode = S_IFLNK | 0777;
        mode_to_prot(inode);

        error = -EIO;
        bh = affs_bread(sb, inode->i_ino);
        if (!bh)
                goto err;
        i  = 0;
        p  = (char *)AFFS_HEAD(bh)->table;
        lc = '/';
        if (*symname == '/') {
                struct affs_sb_info *sbi = AFFS_SB(sb);
                while (*symname == '/')
                        symname++;
                spin_lock(&sbi->symlink_lock);
                while (sbi->s_volume[i])        /* Cannot overflow */
                        *p++ = sbi->s_volume[i++];
                spin_unlock(&sbi->symlink_lock);
        }
        while (i < maxlen && (c = *symname++)) {
                if (c == '.' && lc == '/' && *symname == '.' && symname[1] == '/') {
                        *p++ = '/';
                        i++;
                        symname += 2;
                        lc = '/';
                } else if (c == '.' && lc == '/' && *symname == '/') {
                        symname++;
                        lc = '/';
                } else {
                        *p++ = c;
                        lc   = c;
                        i++;
                }
                if (lc == '/')
                        while (*symname == '/')
                                symname++;
        }
        *p = 0;
        mark_buffer_dirty_inode(bh, inode);
        affs_brelse(bh);
        mark_inode_dirty(inode);

        error = affs_add_entry(dir, inode, dentry, ST_SOFTLINK);
        if (error)
                goto err;

        return 0;

err:
        clear_nlink(inode);
        mark_inode_dirty(inode);
        iput(inode);
        return error;
}

int
affs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
        struct inode *inode = old_dentry->d_inode;

        pr_debug("%s(%u, %u, \"%.*s\")\n",
                 __func__, (u32)inode->i_ino, (u32)dir->i_ino,
                 (int)dentry->d_name.len,dentry->d_name.name);

        return affs_add_entry(dir, inode, dentry, ST_LINKFILE);
}

int
affs_rename(struct inode *old_dir, struct dentry *old_dentry,
            struct inode *new_dir, struct dentry *new_dentry)
{
        struct super_block *sb = old_dir->i_sb;
        struct buffer_head *bh = NULL;
        int retval;

        pr_debug("%s(old=%u,\"%*s\" to new=%u,\"%*s\")\n",
                 __func__, (u32)old_dir->i_ino, (int)old_dentry->d_name.len,
                 old_dentry->d_name.name, (u32)new_dir->i_ino,
                (int)new_dentry->d_name.len, new_dentry->d_name.name);

        retval = affs_check_name(new_dentry->d_name.name,
                                 new_dentry->d_name.len,
                                 affs_nofilenametruncate(old_dentry));

        if (retval)
                return retval;

        /* Unlink destination if it already exists */
        if (new_dentry->d_inode) {
                retval = affs_remove_header(new_dentry);
                if (retval)
                        return retval;
        }

        bh = affs_bread(sb, old_dentry->d_inode->i_ino);
        if (!bh)
                return -EIO;

        /* Remove header from its parent directory. */
        affs_lock_dir(old_dir);
        retval = affs_remove_hash(old_dir, bh);
        affs_unlock_dir(old_dir);
        if (retval)
                goto done;

        /* And insert it into the new directory with the new name. */
        affs_copy_name(AFFS_TAIL(sb, bh)->name, new_dentry);
        affs_fix_checksum(sb, bh);
        affs_lock_dir(new_dir);
        retval = affs_insert_hash(new_dir, bh);
        affs_unlock_dir(new_dir);
        /* TODO: move it back to old_dir, if error? */

done:
        mark_buffer_dirty_inode(bh, retval ? old_dir : new_dir);
        affs_brelse(bh);
        return retval;
}